The subject matter disclosed herein relates to aircraft and engine control systems. More specifically, the subject disclosure relates to aircraft and engine control systems for air intake threat detection and mitigation.
Modern aircraft, including fixed wing and rotary wing aircraft, employ full authority digital engine control (FADEC) systems for engine management. These systems typically include two or more fully redundant and independent control channels, and have no manual backup engine control capability to be employed in the event of full FADEC failure. In addition, the engines often utilize highly reactive inlet guide vanes (IGV's) disposed at or near the engine inlet to control and manage airflow into the engine compressor section. The IGV's are positioned and repositioned throughout the flight envelope to attempt to balance aircraft and engine performance requirements such as power and specific fuel consumption with operability requirements such as surge margin. These requirements are often at odds with each other, making control of the air intake flow critical.
From recent field and flight test experience, it has become known that these engine systems are very sensitive to sudden and dynamic changes in temperature of airflow entering the engine via the air intake. Typically, a temperature sensor located in the inlet of the engine is utilized by the FADEC system to ascertain the temperature of the incoming airflow and manage engine systems, such as the IGV accordingly. When this sensor, however, cannot provide data to the FADEC system quickly enough in cases of rapidly changing inlet temperature, the controls set by the FADEC will be in error, potentially resulting in significant power loss and/or engine stall. Such stall condition may persist for as long as the adverse thermal condition (or thermal threat) is present and may ultimately result in engine damage or flameout. Further, a significant thermal threat can affect all of the intakes of multi-engine aircraft simultaneously.